May 10, 2009
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Can someone explain to me the fundamental understanding of why, when two hydrogen atoms for example, release energy when they form a covalent bond? I can't seem to comprehend. Here is my reasoning, please see if this makes any sense of I am simply going in the wrong direction, I would really appreciate this. I am an undergraduate student loving the sciences and have tried figuring this out all night, it is frustrating me:

The kinetic-molecular theory of matter states that all matter consists of tiny particles (everything from atoms, molecules, or ions) which are in constant motion. This means that atoms, molecules, ions, etc. all have kinetic energy associated with them on the microscopic scale known as thermal energy.

I know bond formation between two hydrogen atoms occurs when two atoms (that are moving very high speeds) are stabilized due to the electrostatic attraction-repulsion stability formed between the electrons and protons of the two atoms. This constitutes a chemical bond.

So, did the kinetic energy of the atoms that was once moving really fast, get converted to heat given off to the surroundings, because the bond formation slowed down the thermal energy of the once separated, fast moving atoms??

I am also having a hard time understanding chemical potential energy in a covalent bond. I know that chemical bond formation within a molecules, gives rise to chemical potential energy due to electrostatic attraction-repulsion stability formed between the electrons and protons of the two atoms.

Is potential energy of a chemical system, for example a molecule, visualized as the energy required to counteract the electrostatic force that holds atoms together, i.e the chemical bond?

So, to break a bond we would need to increase the kinetic energy of the individual atoms so that they overcome the the electrostatic interactions that was holding the bond together?

How do you increase the kinetic energy of an individual atom in order to overcome the potential energy of covalent bond in the molecules? They absorb thermal energy from the surroundings, correct?

Thus chemical potential energy is converted to kinetic energy in bond breaking? But in bond formation kinetic energy (thermal energy) of the atoms is converted to heat and/or light?
 
Mar 11, 2010
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Can someone explain to me the fundamental understanding of why, when two hydrogen atoms for example, release energy when they form a covalent bond? I can't seem to comprehend. Here is my reasoning
You're overcomplicating the situation. Or maybe you're looking for a detailed tutorial on molecular energy.

Two Hydrogen radicals are in search of an electron to complete the duet. They find each other and form a non-polar covalent bond. Energy is released because of Coulombic force that draws them together.
 
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loveoforganic

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I don't see any application of coulombic force here. My understanding is that the energy release is due to the completion of the octets (doublets in the case of hydrogen) as well as the increase in entropy of the electrons, now that they're able to circle about a larger amount of space.
 
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I don't see any application of coulombic force here. My understanding is that the energy release is due to the completion of the octets (doublets in the case of hydrogen) as well as the increase in entropy of the electrons, now that they're able to circle about a larger amount of space.
I think the coulombic forces at play is what gives rise to the chemical potential energy, but like you said, completion of the octets and increase in entropy is what causes the release of energy as heat or light to the surroundings?
 
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BerkReviewTeach

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You are juggling a lot of concepts here that aren't really necessary. The bond between two hydrogen atoms would generate as much energy if the two atoms were moving fast as it would if the two atoms were moving slowly, so the energy released has nothing to do with initial kinetic energy. It has to do with electrostatic attraction of an electron on one atom the the nucleus of the other atom (as docelh pointed out) and the stability resulting from a satisfied outermost shell (as loveoforganic pointed out).

What might make it easier to see is considering the opposite scenario. What if you wanted to pull those two atoms apart from one another? You have to put in energy to break the attractive forces between the two bonded atoms, so bond breaking requires the input of energy. The logical conclusion is that the formation of a bond must therefore release energy. if the two atoms were at rest, then the attractive bonding force could move them towards one another, meaning it could them kinetic energy (heat energy) as the bond was formed. Hopefully this perspective helps a little.
 

wagmanager

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I believe it is for the simple reason that they form a more stable product( with less energy) so extra energy is given off. likewise to break the bond is making the product less stable and therefore they would have higher energy content and thus is endothermic